Endoscopic examination involves insertion of a flexible tube into a body cavity, often to locations deep within the body, such as the stomach, small intestine, and large intestine. In order to perform such procedures, a flexible tube is needed that fully transmits a pushing force from the proximal end to the distal end. Endoscopic examination also requires the flexible tube to translate rotational force applied to the proximal end to the distal end.
The pushability and torque response is typically provided by one or more layers surrounding a lumen. An outer coated braid is often disposed around an inner supporting tubular member that has spiral cuts cut in the wall for flexibility. In such a device, the flexibility or stiffness is often similar along the whole length of the device. After repeated flexing of such tubes, the spiral cut tube ends tend to migrate from the center out to the ends, constricting the spiral at the ends, reducing the tube's inherent flexibility, causing an undesired stiffening effect.
The degree of stiffness and flexibility desired for various portions of an endoscope shaft may depend on the body cavity into which it will be inserted, as well as the particular procedure to be performed. There exists a need for a medical device shaft having varying flexibility along its length.